Pulmonary Embryology/Pediatric Lung disorders

Question 1

lung tissue is derived from..

Answer 1

embryonic endoderm in the yolk sac

Question 2

Pulmonary circualtion vessels is derived from

Answer 2

mesenchyme

Question 3

Week 4

Answer 3

Lung bud moves ventrally into mesoderm “respiration diverticulum”
(primitive foregut epithelial cells invade splanchnic mesenchyme)

Question 4

what happens Day 32?

Answer 4

laryngotracheal groove - out pouching between 4th and 6th brachial arch

Question 5

Week 5

Answer 5

R and L lung buds push into the primordial pleural cavity

Question 6

Wk 6

Answer 6

Descent into the thorax (lung and heart) until pleuroperitoneal foramen close

Question 7

Week 7

Answer 7

descent halted by liver

Question 8

Major events of Months 3-9

Answer 8

lungs grow (glandular)

Question 9

Month 6

Answer 9

surfactant production

Question 10

Month 7

Answer 10

respiratory bronchioles proliferate and alveolar ducts and sacs form

Question 11

Outline of the stages

Answer 11

embryonic –> pseudoglandular –> Canalicular –> Saccular/terminal –> alveolar/postnatal

Question 12

Embryonic

Answer 12

Week 4-7
Formation of the proximal tracheobronchial tree by branching of the foregut endoderm.
Formation from main –> lobar –> segmental (tertiary) –> subsegmental.
Occurs assymetrically and dichotomous

Question 13

Disorders associated with embryonic stage dvmt issues

Answer 13

pulmonary agenesis
tracheoesophagel fistula
Vascular malformation to cause airway compression
Laryngomalacia

Question 14

Pseudoglandular stage

Answer 14

Weeks 8-16
Formation until terminal bronchioles (but not alveoli).
Differentiation of conducting airway epitheilum
Splancnic mesoderm forms cartilage, Smooth muscle and mucus glands.

Question 15

Canalicular

Answer 15

17-26 weeks
Formation of the respiratory bronchioles
Delineation of pulmonary acinus and initial development of pulmonary capillaries. 
Beginning of fetal breating.
Survival is possible - but limited.

Question 16

Diseases associated with canalicular stage

Answer 16

Pulmonary hypoplasia, potter’s syndrome (decreased renal function), diaphragmatic hernia, RDS

Question 17

Saccular/Terminal phase

Answer 17

26-36 weeks, or to term
growth and branching of sacs to increase in number. (alveolar ducts and terminal sacs)
Increase in vascularization! and epithelial differentiation to cause surfactant production increases

Question 18

Alveolar/Postnatal phase

Answer 18

37 weeks to 3 yr
secondary septal formation and True Alveoli (90% occur after birth).
Continued formation of Type I from type II with lengthening of capillaries.
Alevoli thins

Question 19

Pulmonary Arch and capillaries forms from..

Answer 19

6th aortic arch

Question 20

Pulmonary veins form from

Answer 20

outgrowth of left atrium

Question 21

Lungs/airways/chest in children vs. adults

Answer 21

Children have smaller airways - decreased radiance so larger resistance.
Larynx is more anterior and higher, large tongue, floppy epiglottis (for suck and swallow).
Smallest part is cricoid cartilage (adults is vocal cords)
Intercostal muscles are weaker
Diaphram is flat and easily fatigued due to type I muscles.
Increased compliant thorax (due to flat diaphragm)
Horizontal ribs

Question 22

what does a increased compliant thorax mean for infants?

Answer 22

• decreased negative intrathoracic pressure and outward recoil
• decreased tidal volume – prone to atelactasis.
  ultimately cause less effective pump and easily fatigued.

Question 23

PE signs of upper airway obstruction

Answer 23

Stridor, dysphagia, (drooling to avoid swallowing), dypsnea and distress.
No hypoxemia - that is a lower airway problem.

Question 24

larygomalacia

Answer 24

Most common cause of stridor in kids.
Ineffective cartalaginous support of supraglottic structures. 
Early presentation (before 6 months), worse with increase airflow or supine.
Outgrowth by 1 (female) or 2 (male)

Question 25

tracheobronchomalacia

Answer 25

abnormal cartilage of trachea and bronchi to cause problems with exhalation. increased secretion, recurrent wheeze, hoarse cough, and recurrent pneumonia.

Question 26

Causes of Acute Stridor

Answer 26

Croup, Foreign Body, Epiglottitis, Bacterial Trachilitis

Question 27

Croup

Answer 27

``` Laryngotracheobronchitis Most common cause of acute stridor. Viral and mild symptoms due to virus Cough, low grade or no fever, NO drooling. Treatment with steroids ```

Question 28

Epiglottitis

Answer 28

A medical emergency cause of acute stridor. Not seen often due to immunization of H influenza B. Also with strep A and N. Gonnorhea or Hot liquid aspiration. Occurs in older 2-7 year olds. Associated with HIgher fever, drooling, dysphagia and low saturation Tx: intubation and IV antibiotics

Question 29

Bacterial Trachilitis

Answer 29

Acute stridor due to viral croup that progresses or staph aurea to cause edema and purulence. High fever, normal epiglottis, in older kids. recovery is longer than with epiglotitis. Tx: intubation, debrdiement, suctioning, IV antibiotics.

Question 30

Physical exam for lower airway disease

Answer 30

Hypoxemia, Wheeze, crackles

Question 31

Bronchopulmonary dysplasia

Answer 31

decreased number of alveoli due to thickened interstitum and simplification of lung structure. Defined as any baby that needs O2 after due date.

Question 32

RDS vs BPD

Answer 32

RDS is a description of what happens when you are born. - whether at 27 weeks or 40. BPD - use of oxygen after due date (40 wks).

Question 33

causes of hypoxemia

Answer 33

VQ mismatch, hypoventilation, shunt, diffusion, extreme altitude, hemoglobinopathy

Question 34

Causes of acute polyphonic wheeze

Answer 34

Bronchioloitis, viral pneumonia, CF, Heart disease, aspiration pneumonia, asthma

Question 35

are you likely to grow out of asthma

Answer 35

no if you have eczema or allergies

Question 36

Pneumonia causes for birth to one month

Answer 36

strep agulactiae and staph aureus

Question 37

Pneumonia 1month - 5 years causes

Answer 37

strep pneumo

Question 38

Pneumonia 5 y - 18 y

Answer 38

Mycoplasma

Question 39

Tx for Px 1 -5 yrs

Answer 39

amoxicillin

Question 40

what do babies do to prevent atelactasis and maintain minute ventilation

Answer 40

``` increase TV (retractions) increase respiratory rate (tachypnea) grunt to keep oxygen in lungs longer ```

Question 41

Differentials for recurrent Px

Answer 41

immunodeficient, Aspiration Px, CF, airway anomalies, foreign body, TB, neuromucocilliary dysfunction

Question 42

Poor growth is due to..

Answer 42

decreased absorption, decreased intake, increased WOB to cause increased metabolic demand

Question 43

CF effects on lungs

Answer 43

Endobronchitis, bronchiectasis, fibrosis, inflammation, mucus plugging

Question 44

Tx of CF

Answer 44

mechanical, antibiotics, DNase, bronchodilators, enzyme replacement, Fat soluble.